781,901. Code telegraphy. STANDARD TELEPHONES & CABLES, Ltd. Feb. 5, 1954 [Feb. 13, 1953], No. 4105/53. Class 40 (3). In an arrangement for establishing a predetermined time interval, for example the instants at which the start element and the code information elements of a telegraph signal are examined and sampled for regeneration, the time interval is determined by counting a series of regularly - recurring moments at which a reading device associated with a storage device is in reading association with a given stored element of information and adding one in binary notation to a number set up in the said store each time said information element is counted, and the desired time interval is determined when the stored number reaches a predetermined value. In the system described, the time interval is determined by applying specified pulse trains to a sonic delay line having a predetermined delay period and having associated record and read heads so that each passage of a pulse train is recorded and applied to an adding circuit and the time interval is determined by the number of times the pulse train has traversed the delay line. The arrangement described employs a nickel magnetostrictive delay line with a delay period of 5/8 m.sec. so that periods of 10 ms. and 20 ms. are determined by counts of 16 and 32 of the number of passages of the pulse train through the delay line. The sonic line may be used in turn by a number of telegraph lines each of which uses a train of twelve pulses having pulse positions p1 . . . p12 derived from a counter circuit C1 fed with pulses from a 1 megacycle/sec. generator S at times P1 . . . P12. Control pulses Pa, Pb, Pc are obtained from the P pulses by means of delay networks D1, D2, D3. The pulses are fed to a five-position counter C2 having outputs PL2.1 . . . PL2.5 which at every fifth step in conjunction with a pulse from the 12th output of C1 passes a pulse to a ten-position counter C3 having ten outputs PL3.1 . . . PL3.10 so that the combined outputs from counters C2, C3 provide a series of fifty consecutive pulses which are allocated to the various telegraph lines, the thirteenth channel, for example, being selected by the simultaneous recurrence of pulses PL2.3 and PL3.2 from the counters C2, C3 respectively. To the twelve pulses p1 . . . p12 associated with a telegraph line are allocated specific functions-p1, p2 being indicative of the long space and start element respectively, p3 to p7 indicating, in binary form, the time scale, pulses p8 to p10 being used to count the information elements, p11 indicating if a mark element has occurred in the signal and p12 being the mark/space output memory which determines whether the regenerated element to be passed to the outgoing line is a mark or a space. In the normal condition of an incoming line, all the pulses p1 . . . p12 are at zero and the line input is at " mark " providing a negative input. When, Fig. 2, a start element appears on the line, for example No. 13 designated by the pulses PL2.3, PL3.2, the gates G1, G2 open and a positive pulse passes from A20 to a gate G3 which is opened by the pulse Pa at position P2 and operates so that via gates G5 and G7 a 1 is recorded in position p2 and via G6 a 1 is recorded for p7 at time P7, the latter being recorded by the start pulse so that at time 10 ms. the start element is sampled for regeneration. As indicated in Fig. 2, the pulses are passed to G300 and G400 to circuit A10 leading to the recording head at station 1. At a time 5/8 ms. later, the pulse 1 in position p2 is read, amplified at G100 and passed to operate circuit F1a which at time Pa of P2 operates the circuit F3(a) of the adding circuit, Fig. 5, and in the start circuit, Fig. 2, F2 which was restored to F2(b) at time P12 is reoperated to F2a. After the completion of the first cycle p3 to p6 are all zeros and at time Pa of P3, F3b operates and maintains the positive pulse through G13 so that gate G500, Fig. 3, opens to record in 1 in position p3 and the pulse Pc operates F3(c) to remove the potential from the invert lead so that when Fl(a) is operated by the 1 in position P7 it is re-recorded as "1" for p7. At the end of the sixteenth cycle, i.e. 10 ms. after the operation of the start circuit, there are "1's" in the positions p3 to p7, and the interval detector, Fig. 6, operates since F4b is not operated. This circuit operates when p3 to p7 are all "1's" which occurs initially after 16 cycles since p7 was recorded as 1 in response to the start. Subsequently p3 to p7 are all recorded as "1's" after 32 cycles, i.e. 20 ms., so that F4(a) remains operated and at time P12 provides an output to " write P " so that for a space element a "1" is recorded for p12. If the element is a mark, gate G18, Fig. 6, is opened at time P11 so that a "1" is recorded for the pulse p11. In order to ensure that a "1" is recorded in position p12 for the start element a first element space inserter, Fig. 13 (not shown), operates when there are "1's" in positions p3 to p7 and " 0's " in positions p8 to p10. After recording a "1" in position p12 in accordance with the space condition of the start element, the pulse train is again put into the relay line and at the end of the cycle the addition of one causes p3 . . . p7 to become " 0 " and p8 to become "1", indicating that one element has been examined. When this pulse train is again passed to the line, F1a is operated and the gate G101 opens at time PL2.3, PL3.2 to operate the circuit F12 to the "a" position to send a space signal element to the telegraph relay. In response to a mark element at any of the sampling instants 30 ms., 50 ms., &c., the output from the inverter X20 operates relay F12, Fig. 4, to the position b to send a mark element to the output telegraph relay. To ensure that the relay operates to " mark " for the stop element, part from the operation of the input circuit, a circuit, Fig. 11 (not shown), is provided for detecting an interval of 130 ms., this period being represented by the binary number 11111011 set up in the pulse positions p3 ... p10 and the circuit operates to inhibit gate G300, Fig. 3, so that a " 0 " is recorded in position p12 and the telegraph relay is set to mark. After an interval of 5 ms., i.e. 135 ms. from the beginning of the start element, a start cancel circuit is operated by the binary member 10111 set up in the position p6 ... p10 and the pulses operate a circuit so that the " 1 " in position p2 is changed to 0 and a gate G300 in the recording circuit is inhibited so that all the pulses in the positions p2 . . . p12 are recorded as " 0's." The arrangement includes a short-start suppression circuit, Fig. 9 (not shown), operating in such a way that if the start signal element has disappeared at the end of the first cycle, i.e. "1" in position p3 and " 0's " in positions p4, p9, p10, a circuit is operated to open a gate in the start cancel circuit so that p2 and all subsequent p's are recorded as " 0's." Long-space signal condition. The detection and transmission of a long space is effected by a circuit, Fig. 10 (not shown), which is brought into operation by a " 0 " in position p11, i.e. no mark in the signal received and a space detected on the incoming line 130 ms. after the beginning of the start element by the operation of the 130 ms. interval detector circuit, Fig. 11 (not shown). The operation of the long-space circuit effects the recording of "1" in position p1 and also a " 1 " in position p12 so that space is sent continuously to the line. Initially, the elements are counted so that p8, p9, p10 become "1's," but as there is "0" in position p2 the "1's" in those positions are changed to " 0's " by the start cancel circuit and with "1's" in positions p1, p11, p12 the pulse train is circulated in the delay line until the end of the spacing condition is detected by the return of the input line to mark. The adding circuit is made operative so that at the end of 10 ms. a "1" is recorded in the position p7 and a long space start-cancel circuit, Fig. 12 (not shown), is operated to change the " 1 " in position p1 to zero and also to change any "1's" in the time scale p3 . . . p7 to zero.. As there is no " 1" in position p1, the long space register, Fig. 10 (not shown), operates so that the "1's" in positions p11, p12 are recorded as "0's" by the inhibition of the gate G300, and the " 0 " in position p12 moves the telegraph relay to its mark position. The temperature of the sonic line is kept at a predetermined value by an arrangement described in Specification 781,902 divided from the present Specification.